exe extension, take note that although the file is compressed, it's typically a file that will install a program onto a computer. .Zip or .Sit files don't install software - they merely archive a collection of them into one, or they significantly reduce the size of a larger one. Decompressing Files Assuming that you have Winzip or StuffIt installed on your computer, you can access the files archived inside a . Windows' Paint program allows users to make changes to existing graphics, or create brand new ones at no additional cost. Interestingly, we can count at least ten different graphics packages that are more popular and widely used than this free one. While it doesn't offer as many editing tools, it does provide the essentials and it can open/save graphics in . But when one command conflicts with another command - or when one command asks for a process or information that isn't available, the computer returns results that aren't useable. That's an error. A prime example of this kind of error is when users attempt to use software that isn't applicable for their system. Earlier computers didn't have an operating system and if you have experience with the computers of the early eighties, you'll remember that most to them didn't even have a hard drive! These old computers booted an MS-DOS type operating system from drivers stored onto a floppy disk, and in order to use a program, users would remove the boot floppy and then insert a new floppy that contained the program. This is a common occurrence when newer pieces of hardware require the programming of a newer operating system. Sure, one could upgrade the operating system to accommodate the demands of a new piece of hardware, but trouble starts when that new operating system requires new hardware in return. If we're not careful, we could end up replacing almost every hard and soft part of a computer that we own - all in an effort to upgrade! Menu bar - this part of a program displays menu items and menu options. Some of the most common parts of a menu bar grants access to File commands, Open commands, Save commands, and Print commands. An example of an error in this part of an interface would be if an option was missing or grayed out (lighter in color).